Coking process



April 25, 1967 M. o. HOLOWATY ET AL 3,316,155

COKING PROCESS Filed Jan. 25, 1963 6 Sheets-Sheet 1 ii oloflz HBRIQUETTED coALCzooo LBS) PRE HEAT GAS ES l4- (loo F) 1 l' [6 9 30 l 2920 I TAR 51c.( Is an.)

EXCHA 22 ("tqog fisag comsus-non qas f3sso n?) Cob/181E510 A l 37(20,900 1 3) C oOLlh lG Q1 55 EXCESS GAS (16.900 n. 80F) C OK E PRODl/GT (I300 H l 0F) Inventors Michael O, ifolowatg/ Charles R. Jackson.

zfwm/vo e 5% orn April 25, 1967 M. o. HOLOWATY ET AL 3,316,155

COKING PROCESS Filed Jan. 25, 1963 6 Sheets-Sheet 2 30 EXCESS LOW GASTEMP. Z NE COAL l FINES /40 men TEMP. ZONE HEATING eAs l 45 u 0 O L 2cooLmq l ZONE cooune GAS 4 COKE PRODUCT COKE BRAIZE Inverzlors Ml chqelO. .Holowal;

COKING PROCESS 6 Sheets Sheet 5 Filed Jan. 25, 1963 Ap 1967 M. o.HOLOWATY ET AL COKING PROCESS 6 Sheets-Sheet 5 Filed Jan. 25, 1963 o ,+&2 HOUR CYCLE A" HEATING RATES THROUGH PLAsTac ZONE 2 noun DISCHARGEcvcus 2.5F/mm.

2.9 'F/MIN.

L' z HOUR DISCHARGE CYCLE I0 V I2 H 0 U R6 6 WW M at t O m a? V O C x na I J fl. 5O ISN e .M M .mh 4 M 5 a. m M F 2 o E T A R T A E H o A ril25, 1967 M. o. HOLOWATY ET AL 3,316,155

COKING PROCESS Filed Jan. 25, 1963 6 Sheets-Sheet 6 Fig.7

WW? I I IVISI PER M MAXIMUM FLUIDITY 3o DDPM @426C N a" r ATIVEF REL NIT! A L 38 "c 370 80 9 40 NAL c no 3o so 500 Inventors M [chael O-fiolowatg Char! e5 R. Jackson 3 j'f/L'lb /V gu. & 8M

vq-Horrzeg s United States Patent ce 3,316,155 Patented Apr. 25, 1967The present invention relates generally to a process of producingmetallurgical coke from carbonaceous material normally consideredunsuitable for producing metallurgical coke, and more particularly to animproved process of producing satisfactory metallurgical coke from 100%Illinois type coals, including fines of Illinois type coals whichheretofore have not been used for producing satisfactory metallurgicalcoke.

The availability of substantial amounts of Illinois coals makes ithighly desirable to use these less expensive coals, particularly thefines having a particle size smaller than 10 mesh, for the Earlier itwas found possible to use run-of-the-mine Illinois coal for producingmetallurgical coke by employing a two stage coking operation in whichIllinois type coal is subjected to a first low temperature coking heattreatment at a temperature between about 1200 F. and 1500 F. followed bya second stage heating at a temperature of between about 2000 F. and2400" F. In order to produce metallurgical coke from Illinois type coalfines having a particle size less than about l0 mesh, however, it hasbeen found necessary to employ a special combination of steps over andabove the foregoing two stage coking treatment.

It is therefore an object of the present invention to provide a processof producing satisfactory metallurgical coke from Illinois type coalfines having a particle size less than about 10 mesh.

It is a further object of the present invention to provide a process ofcontinuously producing a satisfactory metallurgical coke from 100%Illinois coal having a particle size less than about 10 mesh withoutadmixing a binding agent therewith.

Other objects of the present invention will be apparent to those skilledin the art from the following detailed description and claims when readin conjunction with the accompanying drawing wherein:

FIG. 1 is a schematic block diagram of one embodiment of the presentinvention showing the approximate flow rates of the major processstreams;

FIG. 2 is a schematic block diagram of a modified form of the process ofFIG. 1;

FIG. 3 is a schematic block diagram of a further embodiment of thepresent invention showing approximate flow rates of the major processstreams;

FIG. 4 is a schematic block diagram of a modified form of the process ofFIG. 3;

FIG. 5 is a graph showing the time-temperature relationship ofbriquettes heated in accordance with the pres ent invention at twodifferent rates of heating;

FIG. 6 is a graph showing the relationship between the tumble strengthand rate of heating of briquettes produced according to the presentinvention; and

FIG. 7 is a Gieseler plastometer data curve of Illinois No. 6 coal.

It has been found possible to produce a strong uniformly sizedmetallurgical coke from 100% Illinois coal in particulate form and toachieve the other objects of the present invention by employing a threestage process which comprises 1) preheating 100% Illinois type coal in afinely divided form to incipient fluidity, (2) briquetting the heatedcoal particles by means of briquetting apparatus which is heated to asuificient temperature to production of metallurgical coke;

divided 100% Illinois form a thin shell of coke on each of the saidduring briquetting without metallurgical coke briquettes.

In general, to in the form of briquettes from a particle size of lessthan -10 mesh and preferably at least less than -20 mesh be preheated tothe point of incipient fluidity, just below the point where the coalsoftens and becomes plastic and before actual decomposition orvolatilization of the components of the coal. Generally, Illinois typecoals must be heated to a temperature of between about 500 and 750 F.and preferably between about 600 and 700 F.

particles to incipient fluidity.

curve of Illinois No. 6 coal shows that Illinois No. 6 coal has asoftening temperature of about 385 C. (725 F.). When the coal particlesare heated to just below the softening temperature,

through the plastic stage in a heated briquetting appara- When thebriquetting apparatus is maintained at an elevated temperature above thesolidification temperature heated to coking temperatures.

It has also been further observed that because of the greater advantagein employing very small diameter particles of Illinois coal in thepresent process. Thus, it is advantageous in the present invention toemploy the coal in a very finely divided form, including substantialamounts of mesh fines of Illinois type coals, to form the briquettes. Itis also preferred to have the Illinois coal of a particle size such thatabout 90% is less than 20 mesh, since a large percentage of very finelydivided coal improves the handling strength of the coke briquettes, asevidenced by very high tumble test values of the resulting metallurgicalcoke briquettes.

In order to form satisfactory coal briquettes of finely coal after thecoal is heated to incipient fusion, the hot coal particles arecompressed between heated mold surfaces, such as a roll-type briquettingpress comprising a pair of oppositely disposed briquetting rolls, whichexert a sufi'iciently great pressure to form dense briquettes of thedesired size and which can be heated to a sufficiently high temperatureto provide a surface skin or shell of coke thereon so that the briquettes can be handled and transferred to the coking furnace withoutsubstantial fragmentation and without having the briquettes fusetogether during coking. It is preferred that the briquetting apparatusform briquettes in the shape of ellipsoids or egg-shaped briquetteshaving a major diameter of about two inches. The briquetting apparatusis also preferably adjusted to exert a pressure above about 12,000pounds per square inch to form a very dense briquette structure. Sincegreat pressure during the briquetting operation causes the density ofthe briquettes to increase, making it more difficult for volatile duringcarbonization, it is necessary I employ a low rate of heating thebriquettes during the arbonization or coking operation, particularlyduring the eriod the coal passes through the plastic temperature angewhile volatile components are released. The latter a important in orderto avoid building up internal gas ressure within the briquettes whichcould result in excess racking of the briquettes. Also, the larger thebriquettes, he slower must be the heating range in order to avoid ravinga sharp temperature gradient within the briquette vhich might result instress points forming within the )riquette and causing cracking andeventual breaking of he briquette. It is therefore advisable to use thesmallest :ossible briquette size which provides the necessary gasaermeability in the blast furnace.

The surfaces of the briquetting apparatus which con- ;acts the coalparticles during the formation of the briquettes are heated to atemperature above the carbonization or solidification temperature of thecoal so that during the brief period of a few seconds required by thebriquetting apparatus to compress the coal into dense briquettes a thinskin of coke will be formed about the briquette, but without decomposinga substantial portion of the coal comprising the complete briquette. Itis necessary therefore that the briquetting mold surfaces have atemperature of between about 850 and 1200 F., and preferably betweenabout 900 and 1000 F.

During the treatment of the coal particles from the time they are heatedto incipient fluidity to the time the hot briquettes are discharged fromthe briquetting apparatus, the coal particles and briquettes arepreferably protected against oxidation by means of a protective,nonoxidizing atmosphere, such as flue gas or an inert gas.

From the briquetting apparatus, the hot briquettes having a temperatureof about 6007 F. are immediately and directly discharged while protectedagainst oxidation into a feed hopper having associated therewith acharging means which periodically or continuously feeds the hotbriquettes into a suitable coking furnace, preferably a vertical shaftfurnace, wherein the hot briquettes are gradually and continuouslyheated to form metallurgical coke briquettes containing less than about1% volatile matter.

The carbonization or coking apparatus employed in the present inventionconsists preferably of a vertical shaft or column having three majorzones in direct uninterrupted communication. The uppermost section isthe low temperature zone into which the hot briquettes are fed and inwhich the briquettes are heated directly and gradually by gas heattransfer from their initial briquette temperature of about 600-700 F. toa temperature of about 1500 F., during which time the briquettes moveslowly downwardly through the upper section of the vertical shaftfurnace. The second or central section of the furnace is the hightemperature zone in which the briquettes are heated by gas heat transferand wherein the briquettes can also be heated by conduction heattransfer through the walls of the shaft furnace, if desired. During thepassage of the briquettes through the second or high temperature zone,the briquettes are heated from a temperature of about 1500 F. to atemperature of at least 1800 F. and preferably to about 2000 F. so thatthe briquettes are transformed into metallurgical coke having not morethan about 1% volatile matter remaining therein. At no time is there asharp temperature gradient between the first and second zones of thevertical shaft furnace, nor are the briquettes contacted with gas or awall surface having a temperature more than about 300 F. higher than thetemperature of the briquettes. The third section of the furnace is thecooling zone at the lower end of the vertical shaft furnace in which thehot briquettes are cooled from a temperature of about 2000 F. down to atemperature of between 100 F. and 250 F. by countercurrent passage of acool non-oxidizing gas injected into the column at the lower endthereof. The heated cooling gas, after absorbing heat from the rses tobe released briquettes, passes upwardly through the column and assistsin heating the briquettes in the upper section of the column. Thenecessity of using a water quench to cool the coke briquettes iseliminated.

It has been found that one of in the instant carbonization ormetallurgical coking step and the variable which to a significant degreedetermines the strength of the briquettes is the rate of carbonizationor heating of the briquettes in the vertical coking furnace, and thatthisvariable is more critical in the production of metallurgical cokebriquettes from 100% Illinois type coal than from conventional cokingcoals. Thus, in the present metallurgical coking process the rate. ofheating the coal during the plastic stage must be carefully controlledand limited so that the volatile matter is evolved so slightly that asignificant portion of the tar and heated by-products remain within thebriquette and supply the briquette with its own binder. In FIG. 6 of thedrawing a graph is shown correlating the stability (tumble strength) ofthe coke briquettes with the rate of heating, and it was found that thebriquetes formed by heaing at the lowest rate (23 F./min.) had thehighest stability and hardness values with the smallest amount of dust.Thus, in the present invention it has been found preferable to maintainthe rate of heating of the low fluidity 100% Illinois type coalbriquettes at a rate of between about 15 F. per minute to about 35 F.per minute, particularly during the plastic heating stage.

In the immediately following paragraphs the present invention isdescribed in detail as applied to the production of metallurgical cokebriquettes from 100% Illinois No. 6 coal fines obtained from -10 meshscreening'of run-of-the-mine Illinois No. 6 coal comprising about 28% ofthe raw coal, and beneficiated to the extent of removing a portion ofthe high ash refuse comprising about 7% thereof. The larger particles ofthe fines were crushed so that at least about have a particle size lessthan -20 mesh. The Illinois No. 6 coal used had the following theimportant variables analyses:

Percent Volatile matter (dry basis) 38.2 Ash (dry basis) 6.5 Sulphur 1.0Moisture 9.0 Fixed carbon 55.3

As illustrated in FIG. 1 of the drawing, a 2000 pound quantity of theabove Illinois No. 6 coal is fed from a hopper H and a separator S intoa coal preheater 10, such as an inclined rotary kiln or retort andheated to a temperature sufficient to raise the temperature of the coalfines passing therethrough to about 700 F., the temperature at which theIllinois No. 6 coal fines are at incipient fluidity or just below thesoftening point. The preheated coal preferably protected by anon-oxidizing atmosphere and while at a temperature of about 700 F. isdischarged directly into a briquetting apparatus 11 comprised of a pairof oppositely disposed briquetting rolls 12 having the surface thereofprovided with briquette mold cavities and heated to a temperature ofabout 1000" F. The heated rolls 12 compress the coal fines into compactbriquettes 14 having a generally ellipsoid shape with the major axisthereof being about two inches long. The rolls 12 exert a compressionforce on the coal fines of about 12,000 pounds per square inch, and arerotated at such a speed that the briquettes have a surface layer thereofcarbonized during the time the briquettes remain in contact with therolls 12. The hot briquettes 14 having a temperature of between about600 F. and 700 F. are discharged into a feed hopper 16 wherein theyremain protected by a non-oxidizing atmosphere, such as flue gas.Periodically, a charge of briquettes 14 having a temperature of about600 F. are fed into the top of a vertical coking furnace 20 through aconventional double valve charging system 19 which prevents gasesescaping into the atmosphere from the coking furnace 20.

The coking furnace 20 in the present instance is comprised of avertically disposed cylindrical column 22 about one foot in diameter andabout fifteen feet high.

The hot briquettes 14 on entering the upper or low temperature zone ofthe furnace 20 are contacted by heated non-oxidizing gases risingupwardly through the column 22. The gases which initially contact thebriquettes have a temperature of about 9001000 F. so

that the briquettes are not subjected to a great thermal shock. It isalso desirable to have the gases leave the top of the furnace 20 at atemperature of about 900 F., since considerable precipitation of tarswould result if the ofi-gases were at a much lower temperature andexcess heat losses would result if the off-gases were to have atemperature substantially greater than 900 F.

The temperature and in the upper or low temperature zone is preferablydetergas passing upwardly through the vertical coking furnace Only inthe extreme case is it necessary or desirable to heat the slowly anduniformly heated preferably entirely by the hot gases from their initialtemperature of about 600 F. to a temperature of about 1500 F. Duringthis heating in the low temperature zone, the coal gradually releasesthe major portion of the volatile matter. A portion of the releasedvolatile matter is retained within each briquette to serve as a bindingagent.

Without encountering any sharp temperature gradient or obstructionwithin the column 22, the briquettes move from the low temperature zoneinto the second or high temperature heating zone of the furnace 20comprising about a seven foot middle section of the column 22. In

14. The heated gas has a temperature between about 2000 F. and 2500 F.and preferably a temperature of about 2200 F. when the gas enters thecolumn 22 and effects heating of the briquettes 14 to a temperature ofabout 2000 F. which is sufiicient to produce satisfactory metallurgicalcoke briquettes.

The third section of the coking furnace is the cooling zone in which thehot briquettes are cooled by the countercurrent passage of a cool inertgas, such as flue gas or clean coke-oven gas which is injected into thelower end of the column 22. The cooling gas reduces the temperature ofthe coke briquettes from a temperature of about 2000 F. to a temperatureof between about 100 and 250 F. The cooling gases are, of course,gradually heated as they pass upwardly through the column and conservethereby a substantial amount of heat which is used to heat thebriquettes entering the column 22. In this way a substantial amount ofheat ordinarily drawing.

The modified process illustrated in FIG. 2 of the drawing issubstantially similar to the and illustrated in FIG. 1, but differstherefrom in having gas which is preheated to the desired temperature(about 2200 F.) by passing the gas through a gas preheater 45 spacedfrom the coking furnace 40. The latter modification is used when avertical coking furnace unit has a A further modified process forproducing large volumes (2000 tons per day) of metallurgical cokebriquettes from 100% Illinois type coal in accordance with the presentinvention and wherein the coking furnaces 50 have a diameter of about 30feet and a height of about 50 feet is illustrated in FIG. 3 of thedrawing. In order to practice the process illustrated in FIG. 3, 100%Illinois No. 6 coal of the foregoing size and composition must becrushed by passing through a crusher 51 having a capacity of about 100tons per hour to effect reducing about of the coal to about 20 mesh andthereafter heating the crushed coal by passing through a preheating drum52 having a sufficient capacity to heat the coal to about 700 F. Two hotbriquetting roll presses 53 of sufficient capacity to produce tons perhour of briquettes are required. The hot briquettes having a shell ofcoke formed entirely thereabout are fed directly into the top of threevertical coking furnaces 50, as required. The heat for carbonization ofthe briquettes is supplied entirely by hot gases preheated toapproximately 2100 F. in three pebble-type stoves 56. Two of thepebble-type stoves are operated on alternating combustion and preheatcycles. The third pebble stove is used as a spare. The off-gascontaining tar byproducts and ammonia are sent to the by-productrecovery system which includes two primary coolers 57 and two tarprecipitators 58, a decanter 59, an ammonia still 60, and a saturator 61for recovering tar and amonia from the oif gases.

A still further modified form of the process of the present invention isillustrated in FIG. 4 of the drawing. The process of FIG. 4, whilebasically similar to the process of FIG. 3, differs therefrom primarilyby having by-products. Thus, in the process of FIG. 4, the offgases fromthe top of the furnace are not sent directly to the by-product recoveryarea. Rather, these gases containing tar by-products are fed to one ofthe three pebbletype stoves or other heat transfer surface. The pebblesof the pebble-type stove have a sufliciently low temperature to condensethe tar products and cool the gases, thereby effecting deposition of asubstantial proportion of the tar on the surface of the pebbles. Also, asignificant portion of the heat ordinarily lost in the primary cooler isrecoverd by the pebble stove. The gas is then fed from the stove to theby-product recovery area where 1e remaining tar and ammonia products arestripped "om the gas.

In the latter process three stoves are required and are perated in athree-stage alternating cycle. The first ;age described above is the tardeposition stage. When he pebbles are heated by the oiflgases to atemperature uch that the tar recovery is no longer efficient, the stoves switched to the combustion stage and the off-gases are cut to anotherstove which is at a cooler tar deposition emperature. Coke oven gas andair are fired into the irst stove and the tar deposits are burned fromthe sur- Face of the pebbles. In this way the temperature of the pebblesis brought to approximately 2500 F. at which time air is shut off, thestove purged, and clean coke-oven gas is fed to the hot stove. Thelatter gas is thus preheated to about 2200 F. and sent to the cokingunits to supply the necessary heat for carbonization of the briquettes.In order to complete the cycle the coke-oven gas is passed through thepebbles until the pebbles are cooled to the tar deposition temperature.The preheating stage is considerably longer than the combustion stage,thereby requiring using two of the stoves in series for preheating thetransfer gases while the remaining stove is in combustion stage.

Metallurgical coke briquettes produced by any of the ioregoing specificprocesses results in a substantial economic saving due to the coal usedto form the briquettes having a much lower initial cost and because ofthe more economical use of equipment and the conservation of heat in thecoking process.

The term Illinois type coal as used herein designates banded bituminouscoals having in excess of 12 percent volatile matter and comprised ofdistinct layers or isolated sections of carbon-bearing material, such asvitrain, clarain, fusain, and durain.

We claim:

1. A process of producing metallurgical coke briquettes from 100%Illinois type coal which comprises; preheating 100% Illinois type coalin a finely divided form to incipient fluidity without effectingvolatilization of the coal having a particle size less than mesh sizewith at least 90% being less than -20 mesh, forming briquettes of saidcoal by applying simultaneously pressure and heat to said coal while thecoal remains at said incipient fluidity, said heat applied duringbriquetting being sufiicient to form a thin shell of coke about theentire surface of said briquettes without significantly reducing thevolatile matter content of said briquettes at a rate of between about 15F and 3.5" F. per minute, and gradually heating said briquettes throughthe plastic stage such that at least a portion of the volatile matterreleased by said coal is retained within the said briquettes andsupplies the entire binding agent required for said briquettes, andcontinuing said heating above the carbonization temperature of said coalto form metallurgical coke briquettes having a maximum of about 1%residual volatile matter.

2. A process of producing metallurgical coke briquettes from 100%Illinois type coal which comprises; preheating 100% Illinois type coalin a finely divided form having a particle size less than 10 mesh sizewith at least 90% being less than mesh to incipient fluidity withouteflecting volatilization of the coal, forming briquettes of said coal byapplying simultaneously pressure and heat to said coal while the coalremains at said incipient fluidity, said heat applied during briquettingbeing sufiicient to form a thin shell of coke about the entire surfaceof said briquettes without significantly reducing the volatile mattercontent of said briquettes, charging said briquettes into the upper endof a vertical shaft-type coking unit through which said briquettes aremoved slowly by gravity and gradually heating said briquettes throughthe plastic stage at a rate of heating of between about 1.5 F. and 3.5"F. per minute such that at least a portion f t e OlflIiIe matterreleased by said coal is retained within the said briquettes andsupplies the entire binding agent required for said briquettes,continuing said heating above the carbonization temperature of said coalto form metallurgical coke briquettes having a maximum of about 1%residual volatile matter, and cooling said briquettes below theircombustion temperature.

3. A process of producing quettes from 100% Illinois type coal whichcomprises; preheating 100% Illinois type coal in a finely divided formhaving a particle size less than 10 mesh size with at least being lessthan -20 mesh to incipient fluidity without efiecting volatilization ofthe coal, forming briquettes of said coal by applying simultaneously,pressure and heat to said coal while said coal remains at said incipientfluidity, said heat applied during *briquetting being sufficient to forma thin shell of coke about the entire surface of said briquettes withoutsignificantly reducing the volatile matter content of said briquettes,charging said briquettes into the upper end of a vertical shaft-typecoking unit through which said briquettes are moved slowly by gravityand gradually heating said briquettes through the plastic stage in a lowtemperature zone of said unit at a rate of heating between about 15 F.and 3.5" F. per minute such that at least a portion of the volatilematter released by said coal is retained within the said briquettes andsupplies the entire binding agent required for said briquettes,continuing heating said briquettes above the carbonization temperatureof said coal in a high temperature zone of said unit to formmetallurgical coke briquettes having a maximum of about 1% residualvolatile matter, the heat require-d for said heating of said briquettesin said coking unit being supplied primarily by hot inert gas which isintroduced into the coking unit at the lower end of the said hightemperature zone, and cooling said briquettes below their combustiontemperature before discharging from said unit by introducing cool inertgas into the lower end of said coking unit.

4. A process of producing metallurgical coke briquettes from Illinoistype coal which comprises; preheating 100% Illinois type'coal in afinely divided form having a particle size less than -10 mesh size withat least about 90% being less than 20 mesh to a temperature betweenabout 500 and 750 F. to effect incipient fluidity of said coal withouteffecting volatilization of the coal, forming briquettes of said coal byapplying simultaneously pressure of at least 12,000 pounds per squareinch and heat between a temperature of about 850 and 1200" F. to saidcoal while said coal remains at incipient fluidity, said heat appliedduring briquetting being sufficient to form a thin shell of coke aboutthe entire surface of said briquettes without significantly reducing thevolatile matter content of said briquettes, charging said briquetteshaving a temperature of between about 500 and 750 F. into the upper endof a vertical shaft-type coking unit through which said briquettes aremoved slowly by gravity, gradually heating said briquettes through theplastic stage to a temperature of about 1500 F. in a low temperaturezone of said unit at a rate of between about 15 and 3.5 F. per minutesuch that at least a portion of the volatile matter release-d by saidcoal is retained within the said briquettes and supplies the entirebinding agent required for said briquettes, continuing heating saidbriquettes to a temperature of between about 1800" F. and 2200 F. in ahigh temperature zone of said unit to form metallurgical coke briquetteshaving a maximum of about 1% residual volatile matter, the heat requiredfor said heating of said briquettes in said coking unit being suppliedprimarily by coke-oven gas having a temperature of between about 2000and 2500 P. which is introduced into the coking unit at the lower end ofthe said high temperature zone, and cooling said briquettes to atemperature below about 250 F.

metallurgical coke bribefore discharging from said coking unit byintroducing cool coke-oven gas into the lower end of said coking unit.

5. A process of producing metallurgical coke briquettes from 100%Illinois type coal which comprises; preheating 100% Illinois type coalin a finely divided form having a particle size less than 10 mesh sizewith at least about 90% being less than 20 mesh to a tempera ture ofabout 700 F. to effect incipient fluidity of said coal without effectingvolatilization of the coal, forming briquettes of said coal by applyingsimultaneously pres sure of at least 12,000 pounds per square inch andheat of about 1000 F. to said coal while said coal remains at incipientfluidity, said heat of about 1000 F. applied during 'briquetting beingsuflicient to form a thin shell of coke about the entire surface of saidbriquettes without significantly reducing the volatile matter content ofsaid briquettes, charging said briquettes at a temperature of about600-700 F. into the upper end of a vertical shaft-type coking unitthrough which said briquettes are moved slowly by gravity and graduallyheating said briquettes through the plastic stage to a temperature ofabout 1500 F. in a low temperature zone of said unit at a rate ofbetween about 1.5 and 3.5 F. per minute such that at least a portion ofthe volatile matter released by said coal is retained within the saidbriquettes and supplies the entire binding agent required for saidbriquettes, continuing heating said briquettes to a temperature of about2000 F. in a high temperature zone of said unit to at the lower end ofthe said high temperature zone, and cooling said briquettes to atemperature below about 250 F. before dis-charging from said coking unitby injecting cool coke-oven gas into the lower end of said coking unit.

6. A process as in No. 6 coal.

claim 5, wherein said coal is Illinois References Cited by the ExaminerUNITED STATES PATENTS MORRIS O. WOLK, Primary Examiner. JOSEPHSCOVRONEK, Examiner.

1. A PROCESS OF PRODUCING METALLURGICAL COKE BRIQUETTES FROM 100%ILLINOIS TYPE COAL WHICH COMPRISES; PREHEATING 100% ILLINOIS TYPE COALIN A FINELY DIVIDED FORM TO INCIPIENT FLUIDITY WITHOUT EFFECTINGVOLATILIZATION OF THE COAL HAVING A PARTICLE SIZE LESS THAN -- 10 MESHSIZE WITH AT LEAST 90% BEING LESS THAN -20 MESH, FORMING BRIQUETTES OFSAID COAL BY APPLYING SIMULTANEOUSLY PRESSURE AND HEAT TO SAID COALWHILE THE COAL REMAINS AT SAID INCIPIENT FLUIDITY, SAID HEAT APPLIEDDURING BRIQUETTING BEING SUFFICIENT TO FORM A THIN SHELL OF COKE ABOUTTHE ENTIRE SURFACE OF SAID BRIQUETTES WITHOUT SIGNIFICANTLY REDUCING THEVOLATILE MATTER CONTENT OF SAID BRIQUETTES AT A RATE OF BETWEEN ABOUT1.5*F AND 3.5*F. PER MINUTE, AND GRADUALLY HEATING SAID BRIQUETTESTHROUGH THE PLASTIC STAGE SUCH THAT AT LEAST A PORTION OF THE VOLATILEMATTER RELEASED BY SAID COAL IS RETAINED WITHIN THE SAID BRIQUETTES ANDSUPPLIED THE ENTIRE BINDING AGENT REQUIRED FOR SAID BRIQUETTES, ANDCONTINUING SAID HEATING ABOVE THE CARBONIZATION TEMPERATURE OF SAID COALTO FORM METALLURGICAL COKE